<!doctype html>
<html>

<head>
    <meta charset="utf-8">
    <title>无标题文档</title>
    <style>
        body {
            background: #bbd149;
            margin: 0;
            height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        
        .box {
            height: 50px;
            width: 50px;
            position: relative;
        }
        
        .box::before {
            content: '';
            height: 8px;
            width: 50px;
            background: #000;
            opacity: .2;
            border-radius: 50%;
            position: absolute;
            top: 67px;
            left: 0;
            animation: shadow .5s linear infinite;
        }
        
        .box::after {
            border-radius: 5px;
            background: #fff;
            animation: rotate .5s linear infinite;
            content: '';
            position: absolute;
            left: 0;
            top: 0;
            width: 50px;
            height: 50px;
        }
        
        @keyframes shadow {
            0%,
            100% {
                transform: scaleX(1);
            }
            50% {
                transform: scaleX(1.2);
            }
        }
        
        @keyframes rotate {
            0% {
                transform: translateY(0) rotate(0deg);
            }
            25% {
                transform: translateY(10px) rotate(22.5deg);
            }
            50% {
                transform: translateY(20px) scale(1.1, 0.9) rotate(45deg);
                border-bottom-right-radius: 50px;
            }
            75% {
                ransform: translateY(10px) rotate(67.5deg);
            }
            100% {
                transform: translateY(0) rotate(90deg);
            }
        }
    </style>
</head>

<body>
    <div class="box">
    </div>
</body>

</html>